I've decided to go ten.
1.
Who's Next-The Who
2.
Dark Side of The Moon-Pink Floyd
3.
Avalon-Roxy Music
4.
Quadrophenia-The Who
5.
OK Computer-Radiohead
6.
Close To The Edge-Yes
7.
All Mod Cons-The Jam
8.
Roxy Music-Roxy Music
9.
Selling England By The Pound-Genesis
10.
A Thousand Suns-Linkin Park
I listen to all these albums about once every 2-3 months. I've don't like overlistening to albums too much as I like having that sense of newness when possible.
As for ratings they are all 9.5's to 10's.